Para-Aminobenzoic Acid (PABA)

Para-aminobenzoic acid (PABA), which is a component of pteroylglutamate, was formerly believed to be a vitamin and was often referred to as vitamin B-X due to its role as a provitamin for some bacteria. However, studies over the last few decades have suggested that PABA does not demonstrate vitamin activity in humans because humans are unable to synthesize folate from the chemical.